In a conventional method of detecting a tilt of a signal waveform of an output signal wire in a semiconductor integrated circuit, an arrival time on the “L”-level side of the signal waveform and an arrival time on the “H”-level side thereof are detected by a comparator, and a transition time thereby obtained is converted into the tilt of the waveform as recited in the Patent Document 1.    Patent Document 1: FIGS. 1-3 of the US Patent Document (U.S. Pat. No. 6,278,305)